【单选题】

If you’re among the 24 millionAmericans who work from dusk to dawn, don’t underestimate the physical and emotional costs of punching the clock in the dark.

Compared with day workers, night workers are five times more likely to get stomach diseases, twice as likely to smoke cigarettes or use stimulants, and at higher risk for high blood pressure, heart. attack, and breast cancer.And if you have kids, your divorce risk is three to six times higher than normal.
"You’re out of sync with everything and everybody," saysAcaciaAguirre, MD, PhD, author of an eye-opening new report. Your biological clock is thrown off, too. How to survive: "
A、healthy lifestyle matters even more,"Aguirre says. "Exercise, limit coffee, and fit in 7 to 8 hours of sleep per day.\
What does it mean by "punching the clock" (Line 2, Par
A、1)
A、Working.
B．Striking.
C．Repairing.
D．Sleeping.